Overweight boys who lost weight before puberty reduced their risk of developing type 2 diabetes in adulthood, a study reports.

Danish researchers have discovered that male youngsters who were overweight at age seven, 13 and also in early adulthood increased their risk of developing type 2 diabetes by almost four times.

Those children who lost weight by age 13 and avoided putting it back on, however, were significantly less likely to develop type 2 diabetes.

The University of Copenhagen study team based their findings on the weight of 62,500 men when they were aged seven, then 13 and in early adulthood to establish whether they developed type 2 diabetes between the age of 30-60.

Researcher Dr Jennifer Baker told Reuters Health: "Ours is the first and largest to show if we do this before puberty - and this is a great time for intervention and prevention because children are in school - you can reduce future risks of this disease.

"There's a constant reduction in risk if the weight stays off longer. The game is never over, so to speak."

The results showed that the children who were initially overweight but able to reach a healthy weight before the age of 13 had similar rates of type 2 diabetes as men who had never been overweight.

Children who remained overweight at 13 but reached a healthy weight by adulthood had a 47% increase in risk of type 2 diabetes compared with the men that had never been overweight.

The men who had been overweight throughout the age boundaries, the risk of type 2 diabetes was over four times as high (4.14 times) as the men that had never been overweight.

Dr Baker added: "We see this as encouraging, that there is hope for the future if we can help these children normalise their weight through exercise and lifestyle changes, not just diet. The goal isnt weight loss, but weight normalization, because theyre still growing."